In traditional wireless telecommunications systems, transmission equipment in a base station transmits signals throughout a geographical region known as a cell. As technology has evolved, more advanced equipment has been introduced that can provide services that were not possible previously. This advanced equipment might include, for example, an enhanced node B rather than a base station or other systems and devices that are more highly evolved than the equivalent equipment in a traditional wireless telecommunications system. Such or next generation advanced equipment may be referred to herein as long-term evolution (LTE) equipment. Devices that might be used by users in a telecommunications network can include both mobile terminals, such as mobile telephones, personal digital assistants, handheld computers, portable computers, laptop computers, tablet computers and similar devices, and fixed terminals such as residential gateways, televisions, set-top boxes and the like. Such devices will be referred to herein as user equipment or UE.
A group of LTE-based cells might be under the control of a single entity known as a central control. The central control typically manages and coordinates certain activities with a group of cells such as the scheduling for the transmissions. The modulation and coding schemes might include binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), quadrature amplitude modulation (QAM), or other schemes that will be familiar to one of skill in the art.
Services that might be provided by LTE-based equipment can include broadcasts or multicasts of television programs, streaming video, streaming audio, and other multimedia content. Such services are commonly referred to as multimedia broadcast multicast services (MBMS). An MBMS might be transmitted throughout a single cell or throughout several contiguous or overlapping cells. A set of cells receiving an MBMS can be referred to as a service area. A service area and a region under the control of a central control do not necessarily coincide. For example, a central control might specify that a first subset of cells under its control will deliver a first MBMS and that a second subset of cells under its control will deliver a second MBMS.
The transmission of an MBMS can include two components, a multicast control channel (MCCH) and a multicast traffic channel (MTCH). The MTCH delivers the actual content of the MBMS while the MCCH delivers control information related to the MBMS. The MCCH might include key control information that specifies how the content in the MTCH is to be delivered.
When multiple cells overlap, a UE within the overlapped region can receive transmissions from multiple base stations. It is well known in the art that when a UE receives substantially identical data from a plurality of base stations, the transmissions from the base stations can augment one another to provide a signal of significantly higher quality than would be the case if only one base station were transmitting the signal. That is, a higher signal-to-noise ratio can be achieved when substantially the same data is transmitted at substantially the same time on substantially the same resource as well as the same modulation and coding. A region in which a plurality of substantially identical signals are present is known as a single frequency network, or SFN. In the case where all of the base stations in a service area are transmitting an MBMS with substantially signals, the service area would be an SFN. However, if the base stations were transmitting the MBMS with different signals, for example, on different resource, the service area would not be an SFN.